TIGR has developed a significant infrastructure and tool set for the manual annotation of prokaryotic genomes. As sequencing costs have dropped and new sequencing technology has become available, it has become feasible for small research groups or single laboratories to obtain a genome sequence of their organism of interest. Therefore, there is now a significant group of researchers who have genome sequences they wish to manually annotate but who do not have the infrastructure, tools, or annotation expertise they need. Since 2002 TIGR has been providing researchers with access to the TIGR annotation infrastructure and tools with the Annotation Engine service. Included in the service is automated annotation of the user-submitted genome and the manual annotation tool Manatee, both completely free-of-charge. In addition, we offer a separate 3-day training course on our annotation processes and tools. Our efforts have met with great success;our users indicate high levels of satisfaction with the service, and our user base continues to expand. We currently have 55 user groups who have submitted a total of 86 genomes. On average, 2-3 new user groups join the program each month and seasoned users continue to send us additional genomes. With this application, we seek funds to continue to provide the Annotation Engine service free-of-charge to the research community. We also plan to add several enhancements, including: build a sequence editing tool into Manatee;provide search updates for individual proteins;give users the option of leaving their data in TIGR's databases and accessing it and Manatee over the internet;extend Manatee platforms to include Mac OS X and Windows;export a GenBank accession builder;export our Gene Ontology annotation management programs;incorporate into Manatee our multiple genome annotation tool;and, export our Workflow job scheduling system. This work is relevant to the mission of the NIH in public health because the Annotation Engine service brings the tools of genomic science to the researchers working on organisms that impact human health.